The QA sessions in Figures REF  and REF  are single-turn.
But it is not reasonable to assume that users can always compose in one shot a complicated, compositional natural language question that can uniquely identify the answer in the KB.
As discussed in Section REF , many information seeking tasks, such as exploratory search, require an intensive human-machine interaction over a long-term iterative sensemaking process. Thus, a multi-turn C-KBQA system is more desirable because they allow users to query a KB interactively without composing complicated questions.
For example, [1]} show that users rarely issue complicated questions like
\(\text{``Which super heroes came from earth and first appeared after 2009?''}\) 
